DMA Operations Guide Introduction to the Polycom DMA System
2 Polycom, Inc.
Two-node Cluster Configuration
The two-server configuration of the Polycom DMA system is designed to have
no single point of failure within the system that could cause the service to
become unavailable. To support this, the system is configured as a cooperative
active/active two-node cluster. Both servers are actively registered and can
accept and process calls.
The H.323 network topology and choice of gatekeeper determine which server
receives a call. When a Polycom CMA system is acting as the gatekeeper, it
routes calls destined for the Polycom DMA system to the first server that it
finds available. If the first server isn’t available, it automatically routes the call
to the second server.
In the event of a single server (node) failure, two things happen:
• All current calls that are being routed through the failed node are
terminated. These users simply need to redial the same number. The
gatekeeper automatically routes them to the remaining Polycom DMA
system server and they’re placed back into conference.
• If the failed server is the active web host for the system management
interface, the active user interface sessions end, the web host address
automatically migrates to the remaining server, and it becomes the active
web host. Administrative users can then log back into the system at the
same URL. The system can always be administered via the same address,
regardless of which server is actually the web host.
The Polycom DMA system continuously monitors the used and available
resources on each MCU. If an MCU suffers a catastrophic failure, the Polycom
DMA system adjusts its internal resource counts. All the calls and conferences
on the failed MCU are terminated. But as in a server failure, callers can dial
back into the system using the exact same number that they used for their
initial dial-in. The Polycom DMA system then relocates their new conference
to the best available MCU (provided that there is still sufficient MCU capacity
remaining in the system).
The internal databases within each Polycom DMA system server are fully
replicated to the other node in the cluster. If a catastrophic failure of one of the
database engines occurs, the system automatically switches itself over to use
the database on the other server.
Single-server Configuration
The Polycom DMA system is also available in a single-server configuration.
This configuration offers all the advantages of the Polycom DMA system
except the redundancy and fault tolerance at a lower price. It can be upgraded
to a two-server configuration at any time.
This manual generally assumes a redundant two-node cluster. Where there
are significant differences between the two configurations, those are spelled
out.